1. Field of the Invention
The subject of the present invention is novel heterocyclic compounds that induce fibroblast growth factor receptor (FGFR) dimerization, the process for the preparation thereof and the therapeutic uses thereof. The subject of the present invention is in particular novel compounds with a dimeric structure, as FGFR agonists.
2. Description of Related Art
FGFs are a family of polypeptides synthesized by a large number of cells during embryonic development and by cells of adult tissues under various pathological conditions.
FGF2 (or b-FGF) is the first and the most well-characterized of these growth factors. FGF2 is an 18 kDalton (kDa) protein which induces proliferation, migration and protease production by numerous cells, and in particular endothelial cells, fibroblasts, smooth muscle cells or alternatively bone cells. FGF2 interacts with the cells by means of two classes of receptors, high-affinity receptor tyrosine kinases (FGFRs) and low-affinity heparan sulphate proteoglycan (HSPG) type receptors located at the cell surface and in extracellular matrices. Thus, FGF2 and its receptors represent very relevant targets for therapies aimed at activating processes of angiogenesis, and of regeneration of smooth muscle cells, bone cells and hair-follicle cells.
Moreover, it is known that cell surface receptor tyrosine kinases transmit information through the plasma membrane particularly via mechanisms of dimerization of the extracellular domains of these receptors.
Known ligands capable of activating these dimerization mechanisms are typically natural compounds, such as FGFs, PDGF (Platelet-Derived Growth Factor), VEGF (Vascular Endothelial Growth Factor), EPO (Erythropoietin), G-CSF (Granulocyte-Colony Stimulating Factor), TPO (Thrombopoietin), certain cytokines or insulin.
B. Seed (Chemistry and Biology, November, 1994, 1, 125-129) puts forward the general principle that it would be possible to construct cell receptor agonists by dimerization of antagonists. However, there is no described example of a synthetic molecule constructed according to this concept. Articles such as S A. Qureshi (PNAS, 1999, vol 96, no 21, 12156-12161), B E. Welm (The Journal of cell biology, 2002, vol 157, 4, 703-714), K. Koide (J. Am. Chem. Soc., 2001, 123, 398-408) describe non-peptide compounds or chemical inducers of dimerization (CID), these compounds acting on chimeric receptors and not on natural receptors. They do not present any results showing that a CID makes it possible to activate the signalling pathway of a natural receptor.
In vertebrates, there are 22 members in the family of FGFs with a molecular weight ranging from 17 to 34 kDa and which share between 13% and 71% homology. These FGFs are highly conserved both at the gene level and at the amino acid sequence level. (D Ornitz. & N. Itoh, Fibroblast growth factors. Genome Biology, 30005.1-3005.12, 2001). FGFs interact with cells by means of high-affinity receptor tyrosine kinases (FGF-R1, —R2, —R3, —R4). The expression of FGFs suggests that they have an important role in development. Among the FGF family, FGF-2 is the FGF which has been most widely described. It is an 18 kDa protein which induces proliferation, migration and protease production on various cell types, such as endothelial cells, smooth muscle cells, fibroblasts, pericytes, osteoblasts or hair-follicle cells. Thus, the main therapeutic areas in which FGF2 is involved include neuronal and cardiovascular physiology, nerve regeneration, nociception, tissue repair, homoeostasis, and bone repair.
Thus, FGF2 and its receptors represent very relevant targets for therapies aimed at inducing angiogenesis and arteriogenesis processes (Khurana, R. & Simons, M. Insights from angiogenesis trials using fibroblast growth factor for advanced arteriosclerotic disease. Trends Cardiovasc Med 13, 116-22, 2003). When a blood vessel is obstructed, an ischaemic phase is observed, which induces a decrease in arterial circulation in an organ, thereby leading to a decrease in oxygen concentration in the damaged tissues. It has been shown in vitro and in vivo that several growth factors stimulate angiogenesis and arteriogenesis processes. FGF2 also induces neovascularization in vivo and also the development of collateral vessels after ligature of a vessel in pharmacological models.
Several pieces of evidence demonstrate that FGF2 is also involved in the differentiation of angioblasts into epithelial progenitor cells and thus participates in revascularization following occlusion (Burger, P. E. et al. Fibroblast growth factor receptor-1 is expressed by endothelial progenitor cells. Blood 100, 3527-35, 2002). Thus, strategies aimed at increasing the response of the cells of the vascular tree are suitable strategies for increasing post-ischaemic and in particular cardiac or coronary-artery revascularization (Freedman, S. B. & Isner, J. M. Therapeutic angiogenesis for ischemic cardiovascular disease. J Mol Cell Cardiol 33, 379-93, 2001; Freedman, S. B. & Isner, J. M. Therapeutic angiogenesis for coronary artery disease. Ann Intern Med 136, 54-71, 2002).
As regards the treatment of cardiac ischaemia, one of the most promising clinical trials is a trial in which FGF2 was sequestered in alginate microspheres in the presence of heparin (Laham, R. J. et al. Local perivascular delivery of basic fibroblast growth factor in patients undergoing coronary bypass surgery: results of a phase I randomized, double-blind, placebo-controlled trial. Circulation 100, 1865-71, 1999). After 90 days, all the patients treated with FGF2 showed no ischaemic cardiac symptom. In comparison, in the control group, 3 of the 7 patients had persistent symptoms at 90 days, and 2 patients had recourse to vascular surgery. Interestingly, the benefit of the therapy was maintained after 3 years of follow-up. Furthermore, three clinical trials on the injection of FGF2 into the coronary artery were carried out in the treatment of narrowing of the coronary arteries (Laham, R. J. et al. Intracoronary basic fibroblast growth factor (FGF-2) in patients with severe ischemic heart disease: results of a phase I open-label dose escalation study. J Am Coll Cardiol 36, 2132-9, 2000; Simons, M. et al. Pharmacological treatment of coronary artery disease with recombinant fibroblast growth factor-2: double-blind, randomized, controlled clinical trial. Circulation 105, 788-93, 2002; Unger, E. F. et al. Effects of a single intracoronary injection of basic fibroblast growth factor in stable angina pectoris. Am J Cardiol 85, 1414-9, 2000). The result of these three trials shows that intra-coronary infusions of FGF2 are well tolerated and significantly improve the clinical condition of the patients.
In another phase-I clinical trial, patients with peripheral artery disease leading to claudication received FGF2 injections (Lazarous, D. F. et al. Basic fibroblast growth factor in patients with intermittent claudication: results of a phase I trial. J Am Coll Cardiol 36, 1239-44, 2000). In this context, FGF2 was well tolerated in these patients and the clinical data suggest a beneficial effect of FGF2 in particular on improvement of walking in patients with peripheral disease, for instance Buerger's disease or thromboangiitis obliterans, which affects the distal vascular structures and which is characterized by distal arteritis in the legs, accompanied by pain and ulceration.
In another context requiring improved angiogenesis it has just been clearly demonstrated, in diabetic rats, that vascularization in bioartificial pancreases was much greater when the pancreases were impregnated with microspheres carrying FGF2 (Sakurai, Tomonori; Satake, Akira, Sumi, Shoichiro, Inoue, Kazutomo, Nagata, Natsuki, Tabata, Yasuhiko. The Efficient Prevascularization Induced by Fibroblast Growth Factor 2 With a Collagen-Coated Device Improves the Cell Survival of a Bioartificial Pancreas. Pancreas. 28(3):e70-e79, April 2004). This revascularization thus improves the survival of the implanted bioartificial pancreases and, consequently, the survival of the graft. Thus, FGFs appear to contribute to improving bioartificial pancreatic graft survival in diabetic patients and, more generally, appear to contribute to improving graft revascularization and appear to be involved in graft survival.
In addition to the angiogenesis-inducing effects, FGF2 protects endothelial cells against inducers of apoptosis. It has now been clearly described that FGF2 is an endothelial cell survival factor (Role of Raf in Vascular Protection from Distinct Apoptotic Stimuli: A Alavi, J. D. Hood, R. Frausto, D. G. Stupack, D. A. Cheresh: Science 4 Jul. 2003: Vol. 301. no. 5629, pp. 94-96). Acute respiratory distress syndrome (ARDS) is characterized by cardiovascular and neuropsychiatric problems. In the context of the cardiovascular problems, patients exhibit considerable vascular damage and in particular a high level of induction of endothelial cell apoptosis. Recently, Hamacher et al. have demonstrated that bronchoalveolar lavage fluids from patients suffering from ARDS exhibit pro-apoptotic activity against lung microvascular endothelial cells (Tumor necrosis factor-alpha and angiostatin are mediators of endothelial cytotoxicity in bronchoalveolar lavages of patients with acute respiratory distress syndrome. Am J Respir Crit. Care Med. 2002 Sep. 1; 166(5):651-6: Hamacher J, Lucas R, Lijnen H R, Buschke S, Dunant Y, Wendel A, Grau G E, Suter P M, Ricou B.).
Pre-eclampsia is a pathological condition of the placenta which is associated with a deficiency in vascularization (Sherer, D. M. & Abulafia, O. Angiogenesis during implantation, and placental and early embryonic development. Placenta 22, 1-13, 2001). These deficiencies in vascularization are thought to be due to a deficiency in angiogenesis and to lead to disruptions at the level of the placenta that can result in death of the foetus.
Healing is a tissue regeneration process which does not require treatment in most cases. However, complications can occur, such as infection or the appearance of a keloid scar, which is a pathological scar characterized by a fold of fibrous consistency, or by skin retractions resulting in a loss of elasticity of the skin. The healing phase takes place in 5 stages: The first phase is the inflammatory phase, which is the starting point for the tissue repair. This inflammatory reaction causes vasodilation and increases the permeability of the lesion. The second phase is the angiogenesis phase, which enables the provision of nutrients and oxygen, essential to the cells. The third phase is the migration phase: the renewal (and therefore granulation) tissue is put in place: this is the beginning of the production of the scar. All the connective tissue cells migrate to the centre of the lesion, in particular the fibroblasts and the keratinocytes. The fourth phase is the proliferation phase, which consists of a massive proliferation of the connective tissue cells, and of fibres associated with blood vessel development. The final phase is the maturation phase, which is the longest phase: it lasts from 18 to 24 days. The number of fibroblasts will then decrease, as will the number of blood vessels, so as to result in the end of healing. In the case of diabetic patients, healing is a slow and difficult process which exposes them to chronic wounds that are extremely difficult to heal, often becoming complicated by infectious phenomena which can secondarily lead to amputations. By virtue of their pleiotropic activities, FGFs participate in tissue repair in particular by activating keratinocytes and fibroblasts and by participating in the angiogenesis phenomenon. Thus, FGFs appear to play a role in improving healing in healthy or diabetic patients, both from the point of view of the rapidity of healing and from the point of view of scar quality. It has also been clearly described that the levels of growth factors involved in healing phenomena, and in particular FGFs, decrease very greatly with age. Thus, in elderly patients, the deficiencies and delays in healing are linked to deficiencies in FGFs in the skin.
Glutamate is a putative transmitter of dorsal ganglion neurons and bradykinin is a molecule produced during inflamation that can activate and sensitize nociceptive fibres. In this context, FGF2 could modulate inflammatory pain even though no regulatory effect of FGF2 on nociceptive fibres has been demonstrated in vivo. However, it has been demonstrated that FGF2 completely blocks bradykinin-stimulated glutamate release in vitro (Rydh-Rinder et al. (2001) Regul Pept 102:69-79). Thus, FGFs could play a role in nociception and chronic pain.
Peripheral neuropathy is an axonal or demyelinating attack on the motor and/or sensory peripheral nerve that leads to desensitization of the distal limbs. One of the consequences of the nerve damage may be a perforating ulcer, which is to be particularly feared when there is considerable damage to the profound sensitivity since, in this case, the body's weight has a tendency to always be carried by the same support points. One of the major secondary complications of diabetes is the chronic development of peripheral neuropathy. In this context, it has been demonstrated that FGF2 induces axonal regeneration that could be a therapy of choice in the treatment of peripheral nerve damage and therefore in peripheral neuropathy (Basic fibroblast growth factor isoforms promote axonal elongation and branching of adult sensory neurons in vitro. Klimaschewski L, Nindl W, Feurle J, Kavakebi P, Kostron H. Neuroscience. 2004; 126(2):347-53).
It has been proposed that the FGF system is an essential system of muscle regeneration, and of myoblast survival and proliferation (Neuhaus, P. et al. Reduced mobility of fibroblast growth factor (FGF)-deficient myoblasts might contribute to dystrophic changes in the musculature of FGF2/FGF6/mdx triple-mutant mice. Mol Cell Biol 23, 6037-48, 2003). FGF2 could be exploited in order to promote muscle regeneration, in particular in the case of sarcopenia, of loss of smooth-muscle functionality in the sphincters, and also for the survival and progression of transplanted myoblasts, and in particular in Duchenne muscular dystrophy. Growth factors such as VEGF or FGF2 also appeared to improve myocardial perfusion after ischaemia (Hendel, R. C. et al. Effect of intracoronary recombinant human vascular endothelial growth factor on myocardial perfusion: evidence for a dose-dependent effect. Circulation 101, 118-21, 2000). Furthermore, the vascular network is essential to tissue development and preservation. By promoting the delivery of nutrients, oxygen and cells, the blood vessels assist in maintaining the functional and structural integrity of tissues. In this context, angiogenesis and vasculogenesis make it possible to preserve and perfuse tissues after ischaemia. Angiogenic growth factors such as FGF2 thus promote revascularization for tissue regeneration. Thus, FGF2, by acting directly on skeletal muscle cells and on angiogenesis, would have an effect on the regeneration of dystrophic or normal muscles (Fibbi, G., D'Alessio, S., Pucci, M., Cerletti, M. & Del Rosso, M. Growth factor-dependent proliferation and invasion of muscle satellite cells require the cell-associated fibrinolytic system. Biol Chem 383, 127-36, 2002).
Among the main growth factors, it is now clearly established that systemic administration of FGF2 facilitates bone repair after fracture (Acceleration of fracture healing in nonhuman primates by fibroblast growth factor-2. Kawaguchi H, Nakamura K, Tabata Y, Ikada Y, Aoyama I, Anzai J, Nakamura T, Hiyama Y, Tamura M. J Clin Endocrinol Metab. 2001 February; 86(2), 875-880). The local application of FGF2 in gelatin matrices accelerates bone repair in primates, suggesting the clinical usefulness of FGF2 in the treatment of fractures.
The endogenous overregulation of FGF7 (or KGF) and of FGF18 appears to be an important mechanism for promoting the proliferation, migration and protection of hair follicles in pathological cases or following treatment with a cytotoxic agent (Comprehensive Analysis of FGF and FGFR Expression in Skin: FGF18 Is Highly Expressed in Hair Follicles and Capable of Inducing Anagen from Telogen Stage Hair Follicles. Mitsuko Kawano, Akiko Komi-Kuramochi, Masahiro Asada, Masashi Suzuki, Junko Oki, Ju Jiang and Toru Imamura).